The invention relates to a process for the production of bristle articles, such as brushes, brooms, paintbrushes, combs, mats, etc., which comprises a bristle carrier and bristles, optionally combined into bundles and connected thereto, whereof a plurality bristles are arranged in a spaced manner in at least one row, in that a bristle section is transformed by means of a drawing tool into a double layer and accompanied by the formation of a loop and the loop is fixed with one of its ends to the carrier. The invention also relates to an apparatus for performing the process and to the use of the process and/or apparatus for producing implements of a similar construction.
The production of bristle articles has reached a high technological standard as regards the working speed, but the production of the individual bristles or bristle bundles and their supply to the bristle carrier has remained virtually unchanged for decades, as has the connection of the bristles and bristle carrier, to the extent that mechanical connections are involved. Reference will firstly be made to known connecting or joining processes. In the case of mechanical fixing the wooded plastic or similar bristle carrier has a number of holes corresponding to the number of bristle bundles and into these the latter are wedged, vibrated in, bonded in or anchored by means of a metal anchor as a loop. Processes and apparatuses following this principle already operate at high speeds, because the fixing generally only requires one tool stroke (e.g. DE-AS 1 049 823 and German Patent No. 618 031).
Modern plastic technology has lead in particular over the past few years to the development of processes and apparatuses, with which plastic bristles can be joined together in the plasticized state on a plastic bristle carrier. In the case of a corresponding affinity of the plastics, welding processes are used or the bristle ends are embedded in the soft plastic material of the bristle carrier (e.g. U.S. Pat. No. 4 132 449). The fastening-side ends of the bristles are also melted, so that they are welded together, a thickened portion is optionally formed and then they are pressed onto the carrier which is at least zonally melted on its bristle side. It is finally known in connection with the production of the bristle carrier, e.g. by injection moulding (e.g. U.S. Pat. No. 2 655 409) or foaming to embed the bristles in moulds, in that the bristles or bristle bundles, whose fastening-side end has possibly been previously melted and converted into a thickened portion, are placed in the mould and subsequently the bristle carrier is moulded. Thus, in this case the bristles or bristle bundles are embedded in the carrier material. The latter process and also thermal processes generally lead to a completely satisfactory product from the use standpoint, because the bristle carrier has no holes, or at least no open holes and the bristle bundles terminate cleanly with the bristle carrier side, so that such bristle articles are in particular satisfactory hygienically. In addition, the bristles generally have a higher extraction resistance.
When process natural bristles, it is necessary as a result of the relatively short length thereof to use in the bristle carrier individual blanks corresponding to the bristle length, plus the anchoring length. If the bristle bundle is formed by a loop fixed by means of its camber or bend-round to the bristle carrier, the blanks correspondingly have roughly twice the length. This so-called short-cut technology was subsequently adopted when processing plastic bristles, which are generally produced by extrusion. The extruded monofilaments are brought together to form a bundle strand and then the blanks are cut to length therefrom.
The shaping and supply of individual bristles to the bristle carrier essentially takes place by two methods. If the blank produced has the final diameter of the bristle bundle, then e.g. the cut to length bristles are housed in a magazine in parallel form as a larger group. The magazine is constructed as a parallepipedic container and has in its one wall an opening, into which can be introduced a cutout tube, whose internal diameter corresponds to the external diameter of the bristle bundle and by means of which a bundle can be cut out. Using the cutout tubes the bundles are supplied to the bristle carrier, joined thereto and the cutout tube is retracted (e.g. DE-OS 2 849 510, GB-OS 2 016 917). This process is mainly used for welding the bristles to the bristle carrier, but suffers from a number of disadvantages. It only functions in the case of bristles above a certain diameter, which guarantees the necessary transverse stability of the bristles and also only as from a certain bristle length. However, on cutting out bending and tilting of the bristles occurs in the magazine and this leads to operating problems during the subsequent cutout cycles. If the cutout tube is not completely filled, then bristle bundles or individual bristles can fall out on transfer to the bristle carrier. On discharging the bristles from the cutout tube, frequently individual bristles remain stuck in the tube and during the subsequent cutout operation they need to operational problems. In a similar procedure used in conjunction with welding and injection moulding, the bristles of a bundle are melted at their end to form a thickened portion and the individual bundles are conveyed in lines pneumatically in much the same way as a pneumatic tube, the thickened portion intending to ensure the sealing in the line. However, this process is extremely fault-prone and has not been adopted in practise (EP-OS 0 149 996).
In the method of DE-AS 1 049 823, the bristle blank is mounted on a draw-in tool at right angles to its final position on the bristle carrier. In the centre of the support, the tool has a draw-in opening, which is aligned with the fastening point of the corresponding bristle bundle on the bristle carrier. By means of a drawing tool moving from above to the bristle blank, e.g. in the form of a tongue, the blank is drawn into the draw-in opening accompanied by the formation of a loop until its leading camber passes out at the opposite side of the draw-in tool. By means of this end the bristle bundle is then mechanically fixed to the bristle carrier, in that e.g. it is driven into a hole on the bristle carrier by an anchor carried by the tongue or it is vibrated into the hole. Thermal joining processes or embedding processes are also possible in this way.
For some time plastic bristles have been available, which can be wound up in the form of an endless strand and numerous attempts have been made to carry out processing directly from the roll or spool. The basis for this is either provided by monofilament endless strands, which are in each case placed on a roll (U.S. Pat. Nos. 2 655 409 and 2 710 774). These monofilaments must firstly be combined to a bundle and then the bundle is cut to bristle length or double the bristle length during loop formation and finally the individual bundles are supplied by one of the aforementioned processes to the bristle carrier. For both space and operation reasons this method is only usable for those bristle articles having a relatively small number of bristle bundles, because it is necessary to have for each bristle bundle a plurality of rolls with guide and removal means and all the monofilaments must be brought together on a small diameter. This process is unsuccessful in the case of brooms, hand brushes, etc. These problems can be reduced although not eliminated, if bundle strands and not monofilaments are wound onto the roll, so that only one roll is required for each bristle bundle (DE-AS 1 049 823 and U.S. Pat. No. 4 132 449). However, as a result of the roll diameter, the inadequate creep strength of plastics and the tensile forces required during winding, length differences occur within the bundle, which are extremely disadvantageous during processing. Attempts have already been made to avoid or compensate these length differences, in that monofilaments are twisted within the bundle strand, optionally the strand is wound by the cross-winding process and finally processing takes place under an increased tensile force in order to bring the shorter filaments, by expansion, to the same length as the longer monofilaments. Here again the problem occurs that in the case of a bristle article with a plurality of bundles, e.g. from brooms, scrubbing brushes, mats, etc., a separate roll must be provided for each bundle. This is not very practicable and is uneconomic due to the costs for the rolls, the necessary space requirements and the bundle supply problems.